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Weak credential policy - Temporary passwords

Need​

Enhancement of credential policy for temporary passwords

Context​

  • Usage of C# for developing robust and efficient software applications
  • Usage of _userManager for user management and authentication
  • Usage of _emailSender for sending emails
  • Usage of Controller for managing and handling application logic and data flow
  • Usage of Task for managing asynchronous operations and concurrency
  • Usage of IActionResult for handling and returning HTTP responses in a structured manner
  • Usage of ResetPasswordConfirmation for handling password reset confirmation functionality
  • Usage of the Url module for parsing and manipulating URLs
  • Usage of Request for making HTTP requests
  • Usage of ResetPasswordCallbackLink for generating a link to reset a user's password

Description​

Non compliant code​

public class AccountController : Controller
{
    [HttpPost]
    public async Task<IActionResult> ResetPassword(string email)
    {
        var user = await _userManager.FindByEmailAsync(email);
        if (user == null)
        {
            // Don't reveal that the user does not exist
            return RedirectToAction(nameof(ResetPasswordConfirmation));
        }
        
        var code = await _userManager.GeneratePasswordResetTokenAsync(user);
        var callbackUrl = Url.ResetPasswordCallbackLink(user.Id, code, Request.Scheme);
        await _emailSender.SendEmailResetPasswordAsync(email, callbackUrl);
        
        return RedirectToAction(nameof(ResetPasswordConfirmation));
    }
}

The above code is part of an ASP.NET Core application and it's handling the password reset functionality. When a user forgets their password, they can request a password reset. The system then generates a password reset token and sends it to the user's email address.

The vulnerability lies in the GeneratePasswordResetTokenAsync(user) method. This method generates a temporary password reset token which is not governed by any strong security policy. The generated token might be easily guessable or crackable by attackers, which could lead to unauthorized access to user accounts.

Steps​

  • Implement a strong password policy for temporary passwords.
  • Ensure that temporary passwords meet the minimum requirements for password strength.
  • Enforce a password expiration policy for temporary passwords.
  • Implement multi-factor authentication for password reset process.
  • Consider using a secure password reset mechanism that does not rely solely on email communication.

Compliant code​

public class AccountController : Controller
{
    private readonly IPasswordValidator<AppUser> _passwordValidator;
    private readonly IPasswordHasher<AppUser> _passwordHasher;

    public AccountController(IPasswordValidator<AppUser> passwordValidator, IPasswordHasher<AppUser> passwordHasher)
    {
        _passwordValidator = passwordValidator;
        _passwordHasher = passwordHasher;
    }

    [HttpPost]
    public async Task<IActionResult> ResetPassword(string email)
    {
        var user = await _userManager.FindByEmailAsync(email);
        if (user == null)
        {
            // Don't reveal that the user does not exist
            return RedirectToAction(nameof(ResetPasswordConfirmation));
        }
        
        var tempPassword = GenerateTemporaryPassword();
        var passwordValidationResult = await _passwordValidator.ValidateAsync(_userManager, user, tempPassword);
        if (!passwordValidationResult.Succeeded)
        {
            // Handle password validation failure
            return View("Error");
        }
        
        user.PasswordHash = _passwordHasher.HashPassword(user, tempPassword);
        var result = await _userManager.UpdateAsync(user);
        if (!result.Succeeded)
        {
            // Handle update failure
            return View("Error");
        }
        
        var code = await _userManager.GeneratePasswordResetTokenAsync(user);
        var callbackUrl = Url.ResetPasswordCallbackLink(user.Id, code, Request.Scheme);
        await _emailSender.SendEmailResetPasswordAsync(email, callbackUrl);
        
        return RedirectToAction(nameof(ResetPasswordConfirmation));
    }

    private string GenerateTemporaryPassword()
    {
        // Implement a method to generate a strong temporary password
        // The password should meet the minimum requirements for password strength
    }
}

The updated code now includes a strong password policy for temporary passwords. The GenerateTemporaryPassword method is used to generate a strong temporary password that meets the minimum requirements for password strength.

The IPasswordValidator&lt;AppUser> service is used to validate the temporary password. If the password does not meet the requirements, the method returns an error view.

The IPasswordHasher&lt;AppUser> service is used to hash the temporary password before it is stored in the database. This ensures that the password is stored securely.

The UpdateAsync method is used to update the user's password in the database. If the update fails, the method returns an error view.

The code also includes a password reset token that is sent to the user's email. This token is used to verify the user's identity when they reset their password. This adds an additional layer of security to the password reset process.

This code does not include a password expiration policy for temporary passwords or multi-factor authentication for the password reset process. These features could be added to further enhance the security of the password reset process.

References​

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